>>I just noticed that there is a built-in test StringQ[],
>> that is not documented in the online help
You don't mean "online help", you mean on DISK help. Try searching for
StringQ at Wolfram's online Documentation Center
http://documents.wolfram.com/ and you'll find hundreds of unrelated
articles, in addition to a few that actually mention this function. In
addition, this works:
?StringQ
StringQ[expr] gives True if expr is a string, and False otherwise.
If you look up String in the Help Browser and look at topics under
String Manipulation, StringQ isn't listed, and this is what I call
undocumented: we can't find out about it unless somebody tells us
about it, we see it in a post like this, et cetera. We can't look it
up at the Doc Center or use ? unless we know it exists and we know its
precise name.
By that definition, there are hundreds, probably thousands of
undocumented functions and features. Help for complex topics is poorly
written, too -- apparently by programmers with little or no skill in
writing for an audience.
That said, Mathematica is more complex and better documented than
Visual Basic for Applications, Excel, et cetera, so.... We're lucky.
Bobby
Marcus Stollsteimer <marcus314 at yahoo.com> wrote in message news:<c5o9i7$16q$1 at smc.vnet.net>...
> Hi,
>
> I just noticed that there is a built-in test StringQ[],
> that is not documented in the online help.
>
> ?StringQ
> StringQ[expr] gives True if expr is a string, and False otherwise.
>
> Only a mistake?
> Is it unsafe to use this function?
>
> Regards,
> Marcus